1. Field of the Invention
The invention relates to an optical switch, more particularly to an. optical switch for routing an optical signal at high speeds.
2. Description of the Related Art
Due to the requirement of high-speed data transmission in Internet applications, optical switches are often used in image display, data recording, data transmission and data processing. However, a conventional mechanical optical switch is expensive and has a complicated construction and low reliability. Moreover, the switching speed (e.g., 1 millisecond to 100 milliseconds) of a conventional mechanical optical switch cannot meet the demands of high-speed network communication application.
Generally, conventional mechanical switch includes a deflecting device having a movable deflector. First, two assumptions are made to simplify analysis.                1. The moment of linear displacement of the deflector is greater than, about 3.14 timer, the angular moment of the deflector when tilting.        2. The inertial mass of the deflecting device is about 3.1.4 times that of the deflector.        
If the deflector is made of silicon with a density of 2.33 g/cm3, and has a volume of 90×90×4 μm3, the force f and the power P required to move the deflector by a distance of 1.2 μm within a period of 40 nanoseconds are as follows:
                    f        =                  2          ×          m          ×                      s                          t              2                                                              =                  2          ×          7.55          ×                      10                          -              8                                ×                                    1.2              ×                              10                                  -                  4                                                                                    (                                  4                  ×                                      10                                          -                      8                                                                      )                            2                                                              =                  1.13          ×                      10            4                    ⁢                                          ⁢          dynes          ⁢                                          ⁢                      (                                          1                /                9                            ⁢                                                          ⁢              Newton                        )                                                  P        =                  f          ×                      -                          s              t                                                              =                  1.13          ×                      10            4                    ×                                    1.2              ×                              10                                  -                  4                                                                    4              ×                              10                                  -                  8                                                                                            =                  34          ×                      10            6                    ⁢                                          ⁢          watts          ⁢                                          ⁢                      (                          34              ⁢                                                          ⁢              Megawatts                        )                              
Both the required force f and power P are not available in conventional integrated circuits. Particularly, since it is difficult to apply a force of 1 Newton to a tiny space smaller than a tip of a hair strand, the switching speed of the conventional mechanical optical switch is thus limited to millisecond-levels.
To solve the above problem, various techniques for mechanical optical switches, such as liquid crystal, piezoelectric, sound wave, temperature and electrostatic, lave been proposed heretofore in response to growing requirements. However, the switching speeds of mechanical optical switches using the above techniques can only be promoted to microsecond levels.